String tension and body size?

[Arthur Blake]

Most discussions seem to suggest medium strings on dreadnought, and light on OM size.

Doesn't it stand to reason that shorter sections of wood bracing and tops (assuming same dimensions and stiffness) would have *greater* strength?

[charles Tauber]

Size, per se, is irrelevant. What matters is what the instrument was designed to take. A lightly built guitar of any size that was built for light gauge strings isnt going to do well when fitted with heavy gauge strings.

[dekutree64]

That's a good train of thought, but not the right answer. The smaller guitar will indeed be naturally stiffer, but that just means you can thin the top and/or carve the braces further to loosen it back up.

The reason mediums are recommended for dreads is because so many of them have excessively massive and/or stiff soundboards. OMs are easier to get right, so factories have better luck making them work well with lights. Hand builders have a lot more control and can intentionally make a dread optimized for lights or OM optimized for mediums.

I like lights.

[jonfields45]

OR on a more cynical note... People buy dreadnoughts with the expectation that they are loud; best served with heavier medium gauge strings. Typical buyer of a smaller than dreadnought probably cares more about playability. None of these mass market instruments are built to be returned for repair and most will handle mediums. Might be more about marketing than theoretical edge of destruction string tension.

[pops]

I like a lighter string, but don't like the wimpy bass that comes with them. For the last 30 years I have made up mo own sets using lighter strings, but 52-56 low E depending on the guitar. Balances out very well, but the low E is resonant instead of dead like a 46-47.

[Quickstep192]

Originally Posted by charles Tauber

Size, per se, is irrelevant. What matters is what the instrument was designed to take. A lightly built guitar of any size that was built for light gauge strings isnt going to do well when fitted with heavy gauge strings.

When you say "isn't going to do well", do you mean tone, or do you mean destruction?

I've been tinkering a lot with different gauges using D'Addario's String Tension Pro, but I'm never sure what tension to target. I've been trying to err on the side of safety and targeting between 25lbs and 30lbs, trying to stay closer to 25lbs. Any guidance on what tension is "right" for each string?

[charles Tauber]

Originally Posted by Quickstep192

When you say "isn't going to do well", do you mean tone, or do you mean destruction?

Tone is subjective: destruction, not so much. "Destruction" in this context may simply mean bellying and neck reset. Unless you put high-tension aircraft cables on it, it isn't likely to actually undergo total failure. More likely permanent deformation - creep - over a long period of time.

Any guidance on what tension is "right" for each string?

It depends on the individual instrument and how heavily or lightly built it is. One possible measure is how much the top lifts behind the bridge and how much it lowers in front of the bridge, forming an "S" shaped curve/surface. Another possible measure, over time, you may also see the fingerboard "dive" into the soundhole.

[Quickstep192]

So I'm sort of thinking that waiting for the bridge to pull up or the fingerboard to dive into the sound hole might not be the path I want to take to determine if tension is too high.

That said, I was thinking about how or if tension should vary from string-to-string. For example, with a set of D'Addario lights, the tension on the low E and A is 23lbs and then goes up to about 30lbs for the middle two strings, 29lbs on the b, then down to 25lbs on the high e. Is it normal to have variable tensions for different strings?

I have a guitar that I keep tuned to dadgad and I'd like to build a custom set with gauges appropriate for the tuning, but I've often wondered if I should target the same tension across all six strings, or vary it string to string.

[JLT]

In my admittedly limited experience, it has a lot to do with scale length as well. The shorter the length, the less tension there is on the string when tuned to the same pitch. On my guitars, I've found that going to a medium from a light string results in a stiffer feel, with less ability to "bend" notes, which may be a good thing for the style of music you play. Or not.

But I concur with the people who say that you'd do well to contact the guitar's manufacturer, since they can tell you what actually works with your instrument. The chances are that they've already experimented with the configuration you're exploring.

[Sperry]

I like a lighter string, but don't like the wimpy bass that comes with them.

Last year I was turned on to D'Addario EJ19 Phosphor Bronze Bluegrass 12-56 Acoustic Guitar Strings.

combines the medium gauge bottom strings for increased resonance and volume with light gauge top strings for more comfortable playability and single note bending

String Gauges: Plain Steel .012, .016
Phosphor Bronze Wound .025, .035, .045, .056

[John Arnold]

The smaller guitar will indeed be naturally stiffer, but that just means you can thin the top and/or carve the braces further to loosen it back up.

Smaller guitars should always have thinner tops and smaller bracing. Otherwise, the guitar will tend to sound 'tinny' (weak bass). This fact is well known by most successful makers of small guitars....Martin in particular.
The reason lighter gauge strings are appropriate on a smaller guitar is because a smaller top is less massive, and needs less string energy to vibrate.